There is a growing need for efficient self-contained closed-cycle cryocoolers. Refrigeration to 80K or below is required for many emerging low temperature electronic systems such as for super computers, communications equipment, space craft, military electronic countermeasure systems, magnetometers, and nuclear monitoring and counter-proliferation detectors. This need will rapidly increase as devices employing higher temperature (above 80K) superconductors are developed.
The Stirling cycle cryocooler offers considerable promise for these applications. It has proven to be the most suitable type of small closed-cycle cryocooler for cooling to temperatures in the range of 80K. In addition, Stirling machines may be used over a wide range of refrigeration temperatures, and, with suitable modification, may function as engines converting heat input to shaft power output. Stirling engines offer the advantages of quiet operation and the capability to utilize a wide variety of external heat sources, such as low grade fuels, waste heat, geothermal and solar energy. However, currently available Stirling machines employ reciprocating pistons and are consequently very difficult to balance, generate excessive vibration, and are subject to high drive mechanism forces due to the reversing accelerations.
The present invention defines an improved Stirling cycle machine which employs the Wankel rotary mechanism instead of the reciprocating pistons used in prior art Stirling machines for effecting the compression and expansion cycle. The advantages of this new form of Stirling machine include improved efficiency, reduced drive forces and vibration, extended operating life, the use of simple stationary regenerators, and the capability of being completely balanced with a single passive counterweight.